In the past, manufacturers of electrical heaters or the like have dealt with the problem of supplying electrical power to the filaments of the heater by employing threaded studs that pass through holes in the sheet metal housing of the heater. Grounding is prevented by disposing these studs in a pair of abutting insulators, referred to as male and female insulators, with one insulator portion disposed on the outside of the housing and the other insulator half on the inside of the housing.
At the time of initial assembly, the stud, with one insulator portion located thereon, is passed through a somewhat enlarged hole in the housing, and then the other insulator half is applied from the other side of the housing. A nut and washer are then placed on each end of the stud, to mechanically secure the insulators in place on the housing. Thereafter, electrical assembly of the heater is completed by forming an eyelet in the end of the filament wire or the end of the power wire to fit around the stud. A spade or ring type terminal could be crimped onto the wire ends. After placing the eyelet or terminal onto the stud, a washer and nut are then placed onto the stud and securely tightened. This procedure is repeated on the opposite end of the stud. If parallel wiring to elements is required, two power wires would be required on the one end of the stud.
Although countless numbers of such devices have been used through the years, these assemblies suffer from a large number of disadvantages. First of all, a considerable amount of labor is involved in selecting out the stud, nuts that will threadedly fit on the stud, and a suitable number of lock washers to prevent undesired rotation. Then, at the time of assembly, the worker must bring these components together with eyelets or spade terminals so that the desired electrical relationships can be accomplished.
It is significant to note that this is necessarily a time consuming procedure, requiring the services of a dextrous worker if prohibitively high labor costs are to be avoided. It is also most important to note that a preassembled unit cannot be utilzed inasmuch as the hole in the housing is smaller than the external dimensions of the assembly, so any preassembly of the components onto the stud must be disassembled at the time the actual assembly into place in the housing of the heater or the like is to be brought about.
Other disadvantageous aspects of these prior art devices come to light when heater repair is to be effected, for at such times it is necessary to disassemble two complete male-female assemblies for each defective filament to be replaced. It is therefore to be seen that even the labor associated with the repair of heaters can be considerable because of the painstaking effort involved. Furthermore, if the heater is several years old, the threaded stud may have rusted, making removal of the nuts difficult, which, in turn, jeopardizes the easily cracked male-female insulator portions.